Abstract

A relatively low-temperature molten salt assisted synthesis is developed to prepare MAX phase solid solutions in the Ti₂AlC–V₂AlC system, to be used as precursors for the preparation of heterometallic MXenes Ti_{2 – x}V_xC. When the synthesis temperature is 1000°С, Ti₁V₁AlC, Ti_0.5V_1.5AlC, and Ti_0.2V_1.8AlC samples (despite the formation of a MAX phase and a systematic shift of reflection (002) in response to progressing vanadium-for-titanium substitution) typically feature appreciable amounts of impurity phases, namely Al₂O₃ and vanadium (their reflections are partially overlapping). An increase in synthetic temperature to 1100°С appreciably reduces the amount of impurities and, in a Ti₁V₁AlC sample, decreases the unit cell parameter a, which yet far exceeds the calculated and published values (while the parameter c corresponds with those values). Thermal analysis of Ti₂AlC, Ti₁V₁AlC, and V₂AlC samples in the range 20–1000°С shows that the oxidation resistance decreases in the progress of vanadium-for-titanium substitution in a MAX phase. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) are used to study the microstructure of the prepared Ti₂AlC and V₂AlC phases.

中文翻译：

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Ti2AlC–V2AlC 系统中 MAX 相的合成作为异金属 MXenes Ti2 – xVxC 的前体

摘要

开发了一种相对低温的熔盐辅助合成方法，在 Ti ₂ AlC–V ₂ AlC 体系中制备 MAX 相固溶体，用作制备异金属 MXenes Ti _{2 – x} V _x C 的前驱体。当合成时温度为 1000°С、Ti ₁ V ₁ AlC、Ti _0.5 V _1.5 AlC 和 Ti _0.2 V _1.8 AlC 样品（尽管形成了 MAX 相和系统的反射偏移 (002) 以响应于钒的进展）钛取代）通常具有可观量的杂质相，即 Al ₂ O ₃和钒（它们的反射部分重叠）。将合成温度提高到 1100°С 可显着减少杂质的数量，并且在 Ti ₁ V ₁ AlC 样品中，会降低晶胞参数a，但远远超过计算和公布的值（而参数c对应于那些值）。_{Ti 2} AlC、Ti ₁ V ₁ AlC 和 V ₂的热分析在 20-1000°С 范围内的 AlC 样品表明，在 MAX 相中钒替代钛的过程中，抗氧化性降低。透射电子显微镜 (TEM) 和扫描电子显微镜 (SEM) 用于研究制备的 Ti ₂ AlC 和 V ₂ AlC 相的微观结构。